If we have the same crunch point, all candidates but 5 are excluded from r5c1 ... as long as you spot that column 3 splits (35)(469) and that the 3 or 5 in r2c3 forces the 6 of box1 into the first column.

I was going to remark that it is not necessary to recognise the triplet, but you have now demonstrated that yourself.

On the other hand this was a pretty beastly constellation for direct recognition of {3,5}.
It is nicer when the constraints come directly from existing outliers, as in row9 here.
Row4 and row6 already have the 5s but no 3s yet which makes normal scanning pretty ineffective here.

Sarah,
Seeing what can be in r2c3 and r5c3 isn't conclusive here.
The argument goes in two steps:
- see what can't go in certain cells
- what can't go there must be accomodated in the other cells.

In col3 we already know 4 cells so the other five are free.
- 3 and 5 are seen to be excluded from r4c3, r6c3 and r9c3 (cf George above)
- so the 3 and 5 must occur in the remaining free cells (of col3).

Thanks dotdot. Sometimes it seems the logic comes almost naturally, and other times I have an unexplained block that all of sudden gets unclogged ... as happened here.
Thanks for the patient explanation.

"Quelle Domage" Keith--- I had filled in my crunch point in ink, finishing the puzzle in pencil--- erased the pencil to create the "crunch point" that I published above. The 1 in the bottom right hand corner was erroneously entered (incompletely erased) so your beautifully simple solution would not have worked on a puzzle started from the beginning!

Having reached the same crunch point as George, I managed to miss the obvious point that Box 1 "owns" the 6 in column 1 , so r5c1 can only be 5. So in a total fury I chose to apply the old rule "don't force it, get a bigger hammer" and decided to "see what happens if" r8c9 is a 3 rather than the 1 which was its only other possibility. This with over 40 cells still empty. Oddly enough, this actually led to the correct solution, using only logic and no further guesswork. How embarrassing!